This invention relates to a method for adjusting the relative humidity (hereinafter referred to simply as "humidity") of gas to a fixed value.
Within a tightly closed space, retention of a gas at a fixed humidity can be effected rather easily by use of a saturated aqueous solution. In retaining a gas within a container at a fixed humidity by continuously introducing into the container gas having a substantially constant humidity, however, a large volume of the gas must be continuously supplied to the container. This supply of the gas proves to be quite difficult.
It has been customary to control the humidity of a given gas by means of a constant temperature vessel which incorporates a humidifier and a dehumidifier. In this constant temperature vessel, the gas is automatically maintained at a constant humidity by having the humidifier and the dehumidifier properly started or stopped alternately by means of a sensor and a controller. This method of humidity control, however, requires adoption of a prohibitive apparatus.
An expeditious measure resorted to for the regulation of the humidity of a gas involves the use of two containers, one filled with sulfuric acid and the other with water. A given gas whose humidity is desired to be regulated is divided into two streams, one stream to be passed through the container filled with sulfuric acid and the other stream through the container filled with water, whereafter the streams from the two containers are combined and mixed. It may appear that it would be possible to freely vary the humidity of the mixed gas by suitably selecting the ratio at which the gas is divided into the two streams prior to passage through the two respective containers so that the humidity of the gas could be readily regulated automatically. In actuality, however, it is extremely difficult to have the gas introduced accurately at prescribed ratios into the two containers solely by manual handling of cocks adapted to adjust the apertures in the respective feed pipes. The manual handling of these cocks is quite susceptible of error. Further, the humidity cannot easily be kept at a constant value because the pressure of the saturated vapor is variable with the ambient temperature. This fact constitutes itself another drawback for the method under discussion.
One object of this invention is to provide a method for stably and easily adjusting the humidity of gas to a constant value.
Another object of this invention is to provide an apparatus for easily adjusting the humidity of gas to a constant value.